Ethereum doesn't solve the scaling issues but it does add a lot more features to crypto than bitcoin does. If as you say bitcoin may be replaced but not by ethereum then which coin are you suggesting that should be? Litecoin because they have segwit? A completely different coin? I believe most of the alternative coins would have the same scaling issues if it was adopted in mass.
I'm not prescribing any coin to take over. Personally I'm not at all in favour of a one-coin-to-rule-them-all. However there are projects out there that already scale close to or even beyond VISA/MASTERCARD levels of transactions/sec. Projects that come to mind are bitshares (and Steem), apparently either one of them processes more transactions per day than both ethers combined at the moment and from what I understood have a lot of room to grow still.
And then we have the build up to the reveal of eos at concensus, that promises to blow just about everything out of the water performance wise. If the rumors are correct, then it might be an idea for bitcoin to simply move over to the new tech. Although I seriously doubt if the bitcoin community would be willing to make that move.